Using a nic as a network accelerator to access an external storage

ABSTRACT

Some embodiments provide a method of providing distributed storage services to a host computer from a network interface card (NIC) of the host computer. At the NIC, the method accesses a set of one or more external storages operating outside of the host computer through a shared port of the NIC that is not only used to access the set of external storages but also for forwarding packets not related to an external storage. In some embodiments, the method accesses the external storage set by using a network fabric storage driver that employs a network fabric storage protocol to access the external storage set. The method presents the external storage as a local storage of the host computer to a set of programs executing on the host computer. In some embodiments, the method presents the local storage by using a storage emulation layer on the NIC to create a local storage construct that presents the set of external storages as a local storage of the host computer.

BACKGROUND

In recent years, there has been an increase in the use of hardware offload units to assist functions performed by programs executing on host computers. Examples of such hardware offload units include FGPAs, GPUs, smart NICs, etc. Such hardware offload units have improved performance and efficiency requirements of the host computers by offloading some of the operations that are typically performed by the host computer CPU to the hardware offload unit.

BRIEF SUMMARY

Some embodiments of the invention provide a method of providing distributed storage services to a host computer from a network interface card (NIC) of the host computer. At the NIC, the method accesses a set of one or more external storages operating outside of the host computer through a shared port of the NIC that is not only used to access the set of external storages but also for forwarding packets not related to the set of external storages or the distributed storage service. In some embodiments, the method accesses the external storage set by using a network fabric storage driver that employs a network fabric storage protocol to access the external storage set.

The method in some embodiments presents the external storage as a local storage of the host computer to a set of one or more programs executing on the host computer. In some embodiments, the local storage is a virtual disk, while the set of programs are a set of machines (e.g., virtual machines or containers) executing on the host computer. In some embodiments, the method presents the local storage by using a storage emulation layer (e.g., a virtual disk layer) on the NIC to create a local storage construct. In some embodiments, the emulated local storage (e.g., the virtual disk) does not represent any storage on the NIC, while in other embodiments, the emulated local storage also represents one or more storages on the NIC.

The method forwards read/write (R/W) requests to the set of external storages when receiving R/W requests from the set of programs to the virtual disk, and provides responses to the R/W requests after receiving responses from the set of external storages to the forwarded read/write requests. In some embodiments, the method translates the R/W requests from a first format for the local storage to a second format for the set of external storages before forwarding the requests to the external storage through the network fabric storage driver. The method also translates responses to these requests from the second format to the first format before providing the responses to an NIC interface of the host computer in order to provide these responses to the set of programs.

In some embodiments, the NIC interface is a PCIe (peripheral component interconnect express) interface, and the first format is an NVMe (non-volatile memory express) format. The second format in some of these embodiments is an NVMeOF (NVME over fabric) format and the network fabric storage driver is an NVMeOF driver. In other embodiments, the second format is a remote DSAN (distributed storage area network) format and the network fabric storage driver is a remote DSAN driver. The NIC in some embodiments includes a general purpose central processing unit (CPU) and a memory that stores a program (e.g., an NIC operating system) for execution by the CPU to access the set of external storages and to present the set of external storages as a local storage. In some embodiments, the NIC also includes an application specific integrated circuit (ASIC), which processes packets forwarded to and from the host computer, with at least a portion of this processing including the translation of the R/W requests and responses to these requests. The ASIC in some embodiments is a hardware offload unit of the NIC.

In addition to providing an emulation layer that creates and presents an emulated local storage to the set of programs on the host, the method of some embodiments has the NIC execute a DSAN service for the local storage to improve its operation and provide additional features for this storage. One example of a DSAN service is the vSAN service offered by VMware, Inc. The features of the DSAN service in some embodiments include (1) data efficiency processes, such as deduplication operations, compression operations, and thin provisioning, (2) security processes, such as end-to-end encryption, and access control operations, (3) data and life cycle management, such as storage vMotion, snapshot operations, snapshot schedules, cloning, disaster recovery, backup, long term storage, (4) performance optimizing operations, such as QoS policies (e.g., max and/or min I/O regulating policies), and (5) analytic operations, such as collecting performance metrics and usage data for virtual disk (IO, latency, etc.).

These services are highly advantageous for improving performance, resiliency and security of the host's storage access that is facilitated through the NIC. For instance, the set of host programs that access the emulated local storage do not have insight that data is being accessed on remote storages through network communications. Neither these programs nor other programs executing on the host in some embodiments encrypt their storage access, as the storage being accessed appears to be local to these programs. Hence, it is highly beneficial to use the DSAN services for the R/W requests and responses (e.g., its security processes to encrypt the R/W requests and responses) exchanged between the host and the set of external storages that are made to appear as the local storage.

The preceding Summary is intended to serve as a brief introduction to some embodiments of the invention. It is not meant to be an introduction or overview of all inventive subject matter disclosed in this document. The Detailed Description that follows and the Drawings that are referred to in the Detailed Description will further describe the embodiments described in the Summary as well as other embodiments. Accordingly, to understand all the embodiments described by this document, a full review of the Summary, Detailed Description, the Drawings and the Claims is needed. Moreover, the claimed subject matters are not to be limited by the illustrative details in the Summary, Detailed Description and the Drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth in the appended claims. However, for purpose of explanation, several embodiments of the invention are set forth in the following figures.

FIG. 1 illustrates one manner of using a smart NIC to emulate a local storage that represents several external storages to a virtual machine executing over a hypervisor of a host computer.

FIG. 2 illustrates examples of adapters emulated by the smart NIC.

FIGS. 3 and 4 illustrate two different ways that a DSAN service on a smart NIC serves as a vSAN node in some embodiments.

FIGS. 5 and 6 illustrate two different ways that the smart NIC of some embodiments uses to translate between the NVMe and NVMeOF storage formats.

FIG. 7 illustrates a VM that executes on a smart NIC to implement third party interface (protocols) that are needed to access a third party external storage and that are not natively supported by the smart NIC or the host.

FIG. 8 illustrates a process that some embodiments perform to handle egress communication from the host to a third party external storage.

FIG. 9 illustrates a process that some embodiments perform to handle ingress communication from the third party external storage to the host.

FIG. 10 illustrates a smart NIC emulating a local storage using an external storage and a hardware offload unit driver.

FIG. 11 illustrates a process that the smart NIC OS performs in some embodiments to process an egress communication from the host to an external storage for the example illustrated in FIG. 10.

FIG. 12 illustrates a process that the smart NIC OS performs in some embodiments to process an ingress packet from an external storage to the host.

FIG. 13 illustrate one example of a smart NIC that is used with a host to perform storage emulation.

FIG. 14 illustrates a process performed to process an egress NVMe command by the smart NIC of FIG. 13.

FIG. 15 illustrates another example of a smart NIC that is used with a host to perform storage emulation.

FIG. 16 illustrates a process that is performed to process egress packets from the VM.

FIG. 17 conceptually illustrates an electronic system with which some embodiments of the invention are implemented.

DETAILED DESCRIPTION

In the following detailed description of the invention, numerous details, examples, and embodiments of the invention are set forth and described. However, it will be clear and apparent to one skilled in the art that the invention is not limited to the embodiments set forth and that the invention may be practiced without some of the specific details and examples discussed.

Some embodiments of the invention provide a method of providing distributed storage services to a host computer from a network interface card (NIC) of the host computer. At the NIC, the method accesses a set of one or more external storages operating outside of the host computer through a shared port of the NIC that is not only used to access the set of external storages but also for forwarding packets not related to the set of external storages or the distributed storage service. The NICs are sometimes referred to herein as smart NICs as they perform multiple types of services and operations. In some embodiments, the method accesses the external storage set by using a network fabric storage driver that employs a network fabric storage protocol (e.g., NVMeOF) to access the external storage set.

The method presents the external storage as a local storage of the host computer to a set of programs executing on the host computer. In some embodiments, the local storage is a virtual disk, while the set of programs are a set of machines (e.g., virtual machines or containers) executing on the host computer. In some embodiments, the method presents the local storage by using a storage emulation layer (e.g., a virtual disk layer) to create a local storage construct that presents the set of external storages as a local storage of the host computer. In some embodiments, the emulated local storage (e.g., the virtual disk) does not represent any storage on the NIC, while in other embodiments, the emulated local storage also represents one or more storages on the NIC.

The method forwards read/write (R/W) requests to the set of external storages when receiving R/W requests from the set of programs to the virtual disk, and provides responses to the R/W requests after receiving responses from the set of external storages to the forwarded read/write requests. In some embodiments, the method translates the R/W requests from a first format for the local storage to a second format for the set of external storages before forwarding the requests to the external storage through the network fabric storage driver. The method also translates responses to these requests from the second format to the first format before providing the responses to a NIC interface of the host computer in order to provide these responses to the set of programs.

In some embodiments, the NIC interface is a PCIe interface, and the first format is an NVMe format. The second format in some of these embodiments is an NVMeOF format and the network fabric storage driver is an NVMeOF driver. The NIC in some embodiments includes a general purpose central processing unit (CPU) and a memory that stores a program (e.g., an NIC operating system) for execution by the CPU to access the set of external storages and to present the set of external storages as a local storage. The NIC in some embodiments is implemented as a system on chip (SoC) with multiple other circuit components. For instance, in some embodiments, the NIC also includes an application specific integrated circuit (ASIC), which processes packets forwarded to and from the host computer, with at least a portion of this processing including the translation of the R/W requests and responses to these requests. This ASIC in some embodiments is a hardware offload unit (HOU) of the NIC, and performs special operations (e.g., packet processing operations, response/request reformatting operations, etc.).

In addition to providing an emulation layer that creates and presents an emulated local storage to the set of programs on the host, the method of some embodiments has the NIC execute a distributed storage area network (DSAN) service for the local storage to improve its operation and provide additional features for this storage. One example of a DSAN service is the vSAN service offered by VMware, Inc.

The DSAN services are highly advantageous for improving performance, resiliency and security of the host's storage access that is facilitated through the NIC. For instance, the set of host programs that accesses the emulated local storage does not have insight that data is being accessed on remote storages through network communications. Neither these programs nor other programs executing on the host in some embodiments encrypt their storage access, as the storage being accessed appears to be local to these programs. Hence, it is highly beneficial to use the DSAN services for the R/W requests and responses (e.g., its security processes to encrypt the R/W requests and responses) exchanged between the host and the set of external storages that are made to appear as the local storage.

Although the description of some embodiments refers to emulations of NVMe storage and NVMe storage protocol, in other embodiments other storage protocols may be emulated instead of or in addition to NVMe storages. Similarly, although the description refers to PCIe buses, in other embodiments, other system buses are used instead of or in addition to a PCIe bus. Although certain drivers and protocols are shown as being used by external storages in various embodiments, other embodiments use other drivers or protocols for external storage. The smart NICs described herein are described as having operating software. In some embodiments, this operating software is an operating system that has direct control over the smart NIC without an intervening program or hypervisor. In other embodiments, the operating software is a hypervisor that runs on top of another operating system of the smart NIC. Still other embodiments use just a hypervisor and no other operating system on the smart NIC.

FIG. 1 illustrates one manner of using a smart NIC to emulate a local storage 160 that represents several external storages 140 to one or more virtual machines 112 executing over the operating system (OS) 100 of a host computer. One example of such a machine is illustrated as a virtual machine (VM) 112, which operates over a hypervisor 114 executing on the host OS 100. The host computer has a set of processors that execute its OS, hypervisor and VM. This computer also includes a smart NIC that has a set of processors and a set of hardware offload units that assist in the operation of the host computer. Specifically, in addition to performing traditional NIC operations to forward packets to and from the host computer (e.g., between the machines executing on the host computer and machines executing on other host computers), the smart NIC performs storage emulation operations that represent multiple external storages 140 as the local storage 160 to the machines executing on the host computer. The smart NIC connects to PCIe bus 150 of the host.

The smart NIC in some embodiments is a system on chip (SoC) with a CPU, FPGA, memory, IO controller, a physical NIC, and other hardware components. The smart NIC has an operating system (OS) 120 that includes an NVMe driver 122 and a series of storage processing layers 124-127. The discussion below collectively refers to the software executing on the smart NIC as the smart NIC OS 120. However, in some embodiments, the smart NIC OS is a hypervisor, while in other embodiments a hypervisor executes on top of the smart NIC OS and some or all of the storage processing layers are part of this hypervisor. In the discussion below, the components that are attributed to the smart NIC OS 120 are components of the hypervisor 114 that serves as the smart NIC OS or executes on top of the smart NIC OS in some embodiments. In other embodiments, these are components of a smart NIC OS that is not a hypervisor. In still other embodiments, some of these components belong to the smart NIC OS, while other components belong to the hypervisor executing on the smart NIC OS.

The NVMe driver 122 is a driver for the PCIe bus 150. This driver relays NVMe formatted R/W requests from the host hypervisor 114 to the storage processing layers, and relays responses to these requests from the storage processing layers to the host hypervisor 114. The storage processing layers include an NVMeOF driver 124, a core storage service 125, a DSAN service 126, and a virtual device service 127. The virtual device service includes an NVMe emulator 128.

The smart NIC OS 120 uses the NVMeOF driver 124 in some embodiments to access one or more external storages 140. Specifically, the smart NIC OS 120 emulates a local NVMe storage 160 to represent several external storages 140 to the machines (e.g., VM 112) executing on the host. From the host point of view, the VM 112 operates on the emulated local storage 160 as if it was a local NVMe storage connected through the PCIe bus 150.

To access the external storages 140, the smart NIC (e.g., the NVMeOF driver) uses one or more of its shared ports 130. The shared ports are not only used for the purposes of accessing external storage 140, but are also used for other purposes as well (e.g., used to forward packets to and from destinations other than the external storages). The NVMeOF driver 124 handles the NVMeOF protocols needed for communicating with the external storages 140 through network fabric (e.g., through routers).

The smart NICs illustrated in FIG. 1 as well as in other figures perform operations other than storage emulation. For instance, the smart NICs perform regular packet processing in order to forward packets to and from other destinations outside of the smart NIC's host computer that are not external storages. Examples of such other destinations include machines executing on other host computers. However, the illustration presented in FIG. 1 and the other figures focus on the components of the smart NIC that facilitate the storage emulation operations in order not to obscure the description of some embodiments with unnecessary detail.

The core storage service 125 provides one or more core storage operations. One example of such operations are adapter services that allow the smart NIC to emulate one or more storage adapters, with each adapter logically connecting to one or more external storages 140 and facilitating a different communication mechanism (e.g., transport mechanism) for communicating with the external storages. FIG. 2 illustrates examples of such adapters. In this example, four adapters are illustrated. These include an RDMA storage adapter, a TCP storage adapter, an iSCSI adapter, and an iSER adapter.

Through this interface, an administrator in some embodiments can specify one or more adapters to use to access an external storage, or a set of two or more external storages. In some embodiments, more than one adapter is specified for an external storage when the administrator wants to specify a multipath pluggable storage architecture (PSA) approach to accessing the storage. Once the administrator specifies an adapter, a network manager that provides the interface sends the definition of the specified adapter to a network controller, which then configures the smart NIC to implement and configure a new driver, or reconfigure an existing driver, to access the external storage according to the adapter's specified definition. Different methods for configuring a smart NIC in some embodiments are described in concurrently filed U.S. patent application entitled “Distributed Storage Services Supported by a NIC” with the docket number H046.01, which is incorporated herein by reference.

The DSAN service 126 provides one or more DSAN operations to improve the operation of the emulated local storage 160 and provide additional features for this storage. These operations are performed as the emulated local storage is not really local but rather an emulation of one or more external storages. As such, the DSAN service 126 addresses one or more things that can go wrong in accessing such a virtual “local” storage.

For instance, in some embodiments, the DSAN service provides data resiliency and I/O control that are not generally needed when a host machine is accessing a physical local storage over NVMe. A local drive is not subject to interception over a network and is not prone to packet duplication in the manner of packets sent over a network. These issues arise from emulating the local storage using external storage accessed over a network, therefore the DSAN layer 126 resolves such issues before the data is presented to the higher layers.

In some embodiments, the DSAN operations include (1) data efficiency processes, such as deduplication operations, compression operations, and thin provisioning. (2) security processes, such as end-to-end encryption, and access control operations, (3) data and life cycle management, such as storage vMotion, snapshot operations, snapshot schedules, cloning, disaster recovery, backup, long term storage, (4) performance optimizing operations, such as QoS policies (e.g., max and/or min I/O regulating policies), and (5) analytic operations, such as collecting performance metrics and usage data for virtual disk (IO, latency, etc.).

One example of a DSAN service 126 is the vSAN service offered by VMware, Inc. In some such embodiments, the smart NIC includes a local physical storage that can serve as a vSAN storage node. In other embodiments, the smart NIC does not have a local physical storage, or has such a storage but this data storage cannot participate as a vSAN storage node. In such embodiments, the smart NIC serves as a remote vSAN client node, and its vSAN layer is a vSAN proxy that uses one or more remote vSAN nodes that perform some or all of the vSAN operations and then direct the vSAN proxy what to do.

FIG. 3 illustrates such an approach. As shown, the vSAN proxy 326 uses a remote vSAN client protocol to communicate with the other vSAN nodes 305, which direct the vSAN operations of the vSAN proxy. The vSAN nodes 305 provide some or all of the external storages 140 in some embodiments of the invention. In this example, the network storage driver 324 is an iSCSI driver, although other network storage drivers are used in other embodiments.

In other embodiments, the DSAN service of the smart NIC does not use a remote vSAN client protocol to communicate with the other vSAN nodes. For instance, as shown in FIG. 4, a DSAN service 126 in some embodiments uses a vSAN over NVMeOF protocol 426 to communicate with the other vSAN nodes. This protocol is defined in some embodiments to allow the smart NIC to be a vSAN node that does not have a local physical storage, or has such a storage but this data storage cannot participate as a vSAN storage node. In some embodiments, the emulated local storage 160 (that is defined by one or more external storages 140 through emulation operations of the NVMe emulator 128 of the virtual device service 127 of the smart NIC OS 120) serves as the local storage that allows the smart NIC to be a vSAN node.

The virtual device service 127 has an NVMe emulator 128 that emulates the local NVMe storage 160 to represent the set of external storages 140 that are accessed through the NVMeOF driver 124 and the intervening network. As part of this emulation, the virtual device layer 127 maps outgoing NVMe access commands to external storage access commands, and the incoming external storage responses to an NVMe memory response. When multiple external storages are used, this mapping involves mapping between a storage location in the emulated local storage 160 and a storage location in one or more external storages 140. One example of a virtual device emulator that can be used for the NVMe emulator is the virtual device emulator of the vSphere software of VMware, Inc.

Part of the NVMe emulator's operation also involves this emulator using the hardware offload unit (e.g., an ASIC) of the smart NIC to convert the NVMe access commands from an NVMe-PCIe format to an NVMe format, and to convert the external storage responses received at the emulator 128 from the NVMe format to an NVMe-PCIe format (e.g., to remove PCIe header information from outgoing commands, and to add PCIe header information to incoming responses). This is further described below by reference to FIGS. 5 and 6.

The host OS 100, the hypervisor 114 or the VM 112 in some embodiments have their own drivers (not shown) for sending and receiving data through the PCIe bus 150. The host OS 100, the hypervisor 114 or the VM 112 treats the virtual local storage 160 as a physical local storage, without having to deal with the operations that the smart NIC performs to send data to and receive data from the set of external storages 140.

DSAN services 126 (such as the remote DSAN client of FIG. 3 or the vSAN over NVMeOF of FIG. 4) are two ways of offering disaggregated storage services. Today, many DSANs (e.g., VMware's vSAN architecture) are part of a hyper-converged solution, in which each vSAN node offers both storage and compute functionality. As illustrated by FIGS. 3 and 4, disaggregated storage in some embodiments refers to storage in a system which has some DSAN nodes (e.g., some hardware boxes) that provide only compute functionality and no storage functionality. In some embodiments, one or more DSAN nodes only offer storage functionality and no compute functionality. Such a disaggregated system allows more flexibility in datacenters by allowing the operators of the datacenters to add more storage boxes than compute boxes or more compute boxes than storage boxes, whichever is necessary, rather than adding additional compute boxes with storages whenever additional capacity of only one of those resources is necessary.

FIGS. 5 and 6 illustrate two different ways that the smart NIC of some embodiments uses to translate between the NVMe and NVMe-PCIe formats (e.g., to remove PCIe header from outgoing storage access commands and to add PCIe header information to incoming storage responses). Both of these techniques use a hardware offload unit (HOU) 505 of the smart NIC to perform these operations. This HOU is an ASIC that has multiple packet processing stages that can be configured to remove or add PCIe headers to storage commands and responses to and from the external storages. In both approaches illustrated in FIGS. 5 and 6, the NVMe emulator 128 uses an HOU interface 520 to communicate with the HOU 505.

In FIG. 5, the HOU interface executes on a VM 510 that executes on the smart NIC. The smart NIC OS is a hypervisor and the VM 510 executes on top of this hypervisor in some embodiments. As shown, the NVMe emulator 528 of the virtual device layer 527 communicates with the HOU interface 520 to forward storage access commands and responses for processing by the HOU 505 and to receive processed commands and responses from the HOU 505. In other embodiments, the smart NIC executes the HOU interface on machines (e.g., Pods or containers) other than VMs. One example of an HOU interface and the HOU are the Snap software and hardware offered by Nvidia, Inc. In some embodiments, the HOU Snap software operates on the VM as it requires a different OS (e.g., require Ubuntu) than the smart NIC OS (which might be ESX offered by VMware, Inc.).

In some embodiments, a smart NIC is able to employ HOU drivers that are adapted to the smart NIC OS (e.g., HOU drivers supplied along with the smart NIC operating software or subsequently downloaded, etc.) as the interface with the smart NIC HOU. The HOU drivers that are adapted to run directly on a particular type of operating software are referred to as being “native” to that operating software. In FIG. 6, the HOU interface 520 is implemented as a native HOU driver 610 of the smart NIC. This approach works when the driver is available natively for the smart NIC OS. Otherwise, the driver has to operate in a VM 510 as in FIG. 5.

More generally, a VM is used by the smart NIC of some embodiments to perform other processes and/or support other protocols that are not natively supported by the smart NIC in some embodiments. For instance, FIG. 7 illustrates a VM 710 that executes on a smart NIC OS 700 to implement third party interface 725 (e.g., third party storage protocol) that is needed to access a third party external storage 712 and that is not natively provided by the smart NIC OS or the host OS. In this example, the third party storage interface 725 is part of an interface 520 for a HOU 715 of the smartNIC.

At the direction of the HOU interface 520 (also called the HOU handler), the HOU 715 performs storage command and response processing operations needed to implement the third party storage protocol and to convert between the command and response formats of the host's local storage (e.g., its NVMe local storage) and the third party external storage 712. As shown, the third party storage interface 725 passes storage access commands and receives storage access responses from a shared port 720 of the NIC.

FIG. 8 illustrates a process 800 that some embodiments perform to handle egress communication from the host to a third party external storage. As shown, the process 800 starts (at 805) when a workload VM or an application running on the host generates an NVMe command (with data). At 810, the NVMe command is then encapsulated into a PCI-NVME command (i.e., encapsulated with a PCIe header) at a local storage controller of the host computer, and is forwarded along the PCIe bus to the smart NIC 700. At the smart NIC 700, the PCI-NVMe command is passed (at 815) to the HOU handler 520 running inside of the VM 710.

Next, at 820, the third party storage interface 725 strips off the PCI Headers and passes NVMe command back to the HOU handler 520. To do this, the third party storage interface 725 uses the HOU in some embodiments. The HOU handler next uses (at 825) the smart NIC HOU to change the format of the NVMe command to a command that comports with the third party storage 712, and passes (at 830) this command to the third party storage 712 along a shared port of the smart NIC. In some embodiments, the command is passed to the third party storage 712 as one or more packets transmitted through the network fabric.

FIG. 9 illustrates a process 900 that some embodiments perform to handle ingress communication from the third party external storage to the host. As shown, the process 900 starts (at 905) when it gets a storage-access response (e.g., a Read response) through a shared port of the NIC from the third party external storage 712. At 910, the smart NIC OS determines that the storage-access response is from a third party external storage that needs to be processed by the third party storage interface 725 of the HOU handler 520.

At 915, the HOU Interface 520 gets the storage-access response and provides it to the third party storage interface 725, which then converts (at 920) the storage-access response from a third party format to an NVMe format and passes the storage-access response back to the HOU interface 520. Next, at 925, the HOU interface encapsulates the NVMe storage-access response with a PCIe header, and is passed to the host's local storage controller along the PCIe bus 150. The local storage controller then removes (at 930) the PCIe header, and provides the NVMe storage-access response to a workload VM or an application running on the host.

As described with respect to FIG. 1, the smart NICs of some embodiments provide a DSAN service to perform various security and efficiency operations for the virtual local storage that is emulated with one or more external storages. However, the smart NIC in other embodiments bypasses the DSAN layer that performs DSAN operations in order to increase the speed of data transfer. Instead of the HOU drivers described above, some such embodiments use other protocols. For example, some embodiments use HOU upper level protocols (ULP). Upper level protocols (e.g., IPoIB, SRP, SDP, iSER, etc.) facilitate standard data networking, storage and file system applications to operate over InfiniBand.

FIG. 10 illustrates a smart NIC emulating a local storage for the VMs 112 of a host 1000 by using an external storage 1040 and a HOU driver 1022. Like the above-described HOU interfaces and drivers, the HOU driver 1022 forwards data messages for processing by the smart NIC HOU 505 and receives processed data messages from the HOU 505. Specifically, the HOU driver 1022 uses the HOU 505 to perform the packet processing needed to convert between the data message NVMe formats and the NVMe PCIe formats. In this example, the HOU driver 1022 exchanges data messages with a kernel NVMe layer 1028, which exchanges data messages with an NVMe RDMA driver 1024 and/or an NVMe TCP driver 1026. The NVMe RDMA and TCP drivers send and receive data messages to and from external storage 1040 through an intervening network fabric (e.g., intervening routers and switches).

One advantage of the approach of FIG. 10 is that the smart NIC 1020 transfers data quickly between the host and the external storage 1040 that is used to emulate the host's local storage 1020. This transfer is fast because it uses the kernel NVMe 1028 as a bridge and it does not use a DSAN layer 1030 on the smart NIC OS 1020. This embodiment can tap into NVMe RDMA offload capability by using the NVMe RDMA driver 1024. In some embodiments, the HOU of the smart NIC 1020 can strip Ethernet headers from an incoming data packet, identify the particular NVMe PCIe controller (here, the HOU ULP driver 1022) that needs to receive the packet, and pass the packet to that NVMe PCIe controller. Thus, the smart NIC CPU cost of bridging through the kernel NVMe layer 1028 is minimal. This speed comes at a cost of other features, such as bypassing the DSAN service 1030 which provides useful security and performance operations for the emulated local storage.

In the example of FIG. 10, the DSAN module 1056, the virtual device emulator 1057 and the multipath PSA service 1055 are provided for one or more VMs 112 through the host hypervisor 114. Specifically, in this example, a multipath PSA layer 1055 exists between the VMs 112 executing on the host OS 1000 and the NVMe PCIe driver 1060 of the OS. Through this PSA layer 1055, the host can use multiple paths to the same external storage by using different NVMe PCIe drivers executing on the host OS 1000 (although only one NVMe PCIe driver 1060 is shown in FIG. 10). In other words, for the multi-pathing, different PCIe drivers are also used in some embodiments to access the same external storage through different paths. Also, in some embodiments, the different NVMe PCIe drivers are used to emulate different local storages from different external storages 1040.

The virtual device emulator 1057 is used to emulate a local virtual disk from several external storages 1040 for one or more VMs 112. As mentioned above, the vSphere software's virtual device layer is used to implement the virtual device emulator of the host hypervisor or smart NIC hypervisor in some embodiments. In some embodiments, the same or different PCIe drivers 1060 are used to access different external storages 1040 that are used to emulate one virtual disk. The DSAN module 1056 performs DSAN services like those described above for the emulated local storages.

In some embodiments, the host hypervisor and smart NIC hypervisor can be configured to provide different storage services for different workload VMs 112. For instance, the storage access commands and responses for one workload VM is processed by the storage services 1055-57, while the storage access commands and responses for another workload VM skip these storage services. Similarly, the storage access commands and responses of one workload VM is processed by the storage services 125-127 of the smart NIC as shown in FIG. 1, while the storage access commands and responses of another workload VM are just processed by the kernel NVMe module 1028 and NVMeOF drivers 1024 and 1026 of FIG. 10.

FIG. 11 illustrates a process 1100 that the smart NIC OS 1020 performs in some embodiments to process an egress communication from the host to an external storage for the example illustrated in FIG. 10. As shown, the process starts (at 1105) when an NVMe command (with data) is generated by a VM 112 on the host. This packet (at 1110) is encapsulated with PCIe header information to produce a PCIe-NVMe command (with data) at a local storage controller (not shown) of the host, and is passed along to the PCIe bus 150. Next, at 1115, the HOU driver 1022 (e.g., HOU ULP driver) receives this command through the PCIe bus 150, and uses the HOU to strip out the PCI headers and produce the NVMe command (with data).

At 1120, the HOU driver 1022 passes the NVMe command to the kernel NVMe module 1028, which maps this packet to an NVMeOF transport controller. The kernel NVMe module 1028 in some embodiments is transport agnostic, and can be configured to use any one of a number of different NVMe transport drivers. At 1120, the kernel NVMe 1028 identifies the NVMeOF controller (i.e., NVMe RDMA controller 1024 or NVMe TCP controller 1026) that needs to receive this NVMe command. This identification is based on the NVMe command parameters that identify the transport protocol to use. These command parameters are provided by the host's multipath PSA layer 1055.

The kernel module (at 1125) passes the NVMe command to the identified NVMeOF controller, which then generates one or more NVMeOF packets to forward (at 1130) the NVMe command to the destination external storage through a shared port of the smart NIC. As mentioned above, both NVMe RDMA 1024 and NVMe TCP 1026 are provided by the smart NIC OS 1020 for accessing remote external storages 1040 through the shared port(s) 130 of the smart NIC. In some embodiments, the kernel NVMe 1028 works like a multiplexer that provides NVMe storage access to the HOU driver 1022 using different transports, such as NVMe RDMA 1024 and NVMe TCP 1026, at the same time. After 1130, the process 1100 ends.

FIG. 12 illustrates a process 1200 that the smart NIC OS 1020 performs in some embodiments to process an ingress packet from an external storage to the host. As shown, the process starts (at 1205) when an external storage 1040 generates and forwards an NVMeOF command (with data) that is received as a set of one or more network packets at a shared port of the smart NIC through network fabric (e.g., through one or more switches and/or routers). The port (at 1210) passes the received packet to the NVMe RDMA controller 1024 or NVMe TCP controller 1026 depending on the transport protocol used by the external storage. The NVMe controller (at 1215) receives the NVMeOF packet in its transport specific format, removes the transport header data, and provides an NVMe command (with data) to the kernel NVMe 1028.

At 1220, the kernel NVMe 1028 maps the received NVMe command to the HOU driver 1022 as the NVMe command needs to go to host. In some embodiments, the kernel NVMe 1028 creates a record when it was processing an egress packet at 1125 and uses this record to perform its mapping at 1220. In some embodiments, the kernel NVMe 1028 provides the NVMe command to the HOU driver 1022 with the controller of the emulated local storage 160 as the command's destination. At 1225, the HOU driver 1022 then encapsulates the NVMe command with a PCIe header by using the smart NIC's HOU and then sends the NVMe command along the host PCIe to the local storage controller of the emulated local storage 160. The host PCIe then provides (at 1230) the NVMe command to the local storage controller through the NVMe PCIe driver 1060. This controller then removes (at 1230) the PCIe header and provides the NVMe command to the destination VM 112. The process 1200 then ends.

In some embodiments, the smart NICs are used as storage access accelerators. FIGS. 13 and 15 illustrate two such examples. FIG. 13 illustrates how a smart NIC serves as a network accelerator to one or more workload VMs 1312 executing over a host hypervisor 1314 that operates over a host OS 1300. In this example, the remote storage services protocol is running inside the host and the smart NIC OS 1320 just runs network accelerators. Also, the host hypervisor 1314 provides emulation services in this example that allow it to present one or more external storages 1340 as a local storage to a VM 1312. In some embodiments, the hypervisor 1314 is the ESX hypervisor of VMware, Inc. In some such embodiments, a virtual NVMe device emulation module 1311 of the VMware vSphere software provides the NVMe device emulation that presents multiple external storages 1340 as a single local NVMe storage to the VM 1312.

In some embodiments, the hypervisor 1314 also includes the DSAN service layer 1313, which provide distributed storage services for the emulated local NVMe storage. As mentioned above, the distributed storage services in some embodiments account for the VM 1312 having no knowledge regarding the plurality of external storages being used to emulate the local storage. These DSAN service improve this emulated storage's operation and provide additional features for it. Examples of such features in some embodiments include (1) data efficiency processes, such as deduplication operations, compression operations, and thin provisioning, (2) security processes, such as end-to-end encryption, and access control operations, (3) data and life cycle management, such as storage vMotion, snapshot operations, snapshot schedules, cloning, disaster recovery, backup, long term storage, (4) performance optimizing operations, such as QoS policies (e.g., max and/or min I/O regulating policies), and (5) analytic operations, such as collecting performance metrics and usage data for virtual disk (IO, latency, etc.) One example of a DSAN service is the vSAN service offered by VMware vSphere software. The DSAN service layer 1313 also includes a multipathing PSA layer in some embodiments.

The DSAN service module 1313 receives and sends storage related NVMe commands from and to the kernel NVMe module 1315. The kernel NVMe module 1315 interacts with either the NVMe RDMA driver 1316 or NVMe TCP driver 1317 to receive and send these NVMe commands. These drivers exchange these NVMe commands with the smart NIC OS 1320 through one or more virtual functions (VFs) 1322 defined for these drivers on the smart NIC OS.

In some embodiments, the smart NIC OS can present the smart NIC as multiple physical functions (PF) connected to the host computer. The PCIe bus 150, in some embodiments, allows for the creation of these PFs. A PF, in some embodiments, can be further virtualized as multiple virtual functions (VFs). More specifically, in some embodiments, physical functions and virtual functions refer to ports exposed by a smart NIC using a PCIe interface to connect to the host computer over the PCIe bus. A PF refers to an interface of the smart NIC that is recognized as a unique resource with a separately configurable PCIe interface (e.g., separate from other PFs on a same smart NIC). In some embodiments, each PF is executed by the processing units (e.g., microprocessors) of the host computer.

The VF refers to a virtualized interface that is not fully configurable as a separate PCIe resource, but instead inherits some configuration from the PF with which it is associated while presenting a simplified configuration space. VFs are provided, in some embodiments, to provide a passthrough mechanism that allows compute nodes executing on a host computer to receive data messages from the smart NIC without traversing a virtual switch of the host computer. The VFs, in some embodiments, are provided by virtualization software executing on the smart NIC. In some embodiments, each VF is executed by the processing units (e.g., microprocessors) of the smart NIC.

The VFs and PFs, in some embodiments, are deployed to support storage and compute virtualization modules. For example, a PF or VF can be deployed to present a storage or compute resource provided by the smart NIC as a local device (i.e., a device connected to the host computer by a PCIe bus). Defining such VFs are further described the concurrently filed, above incorporated applications entitled “Distributed Storage Services Supported by a NIC” with the Attorney Docket H046.01

The PF 1370 on the host has the corresponding VF 1322 on the smart NIC. The PF 1370 represents a shared NIC port to the NVMeOF drivers 1316 and 1317, which run on the host and convert the NVMe storage access commands to network packets. These drivers use this representative port 1370 to forward storage access packets to an external storage through the VF 1322 of the smart NIC 1320, and to receive storage access response packets from the external storage 1340 through the VF 1322 of the smart NIC 1320.

When the VF 1322 does not know how to process a packet (e.g., when it receives a first packet of a new flow for which it does not have a forwarding rule), the VF passes the packet through a “slow-path” that includes the virtual switch 1326 of the virtualization layer 1327, which then determines how to forward the packet and provides the VF with forwarding rule for forwarding the packet. On the other hand, when the VF 1322 knows how to process a packet (e.g., when the VF receives another packet of a flow that it has previously processed and/or for which it has a forwarding rule), the VF passes the packet through a “fast-path,” e.g., passes a packet of a previously processed flow directly to the NIC driver 1325 for forwarding to an external storage 1340. Accordingly, in the example illustrated in FIG. 13, the VF 1322 is a network accelerator that facilitates the forwarding of the packets related to the external storages.

In some embodiments, the VF 1322 uses the smart NIC HOU 505 to perform its fast path forwarding. When the HOU is not programmed with flow-processing rules needed to process a new flow, the VF 1322 in some embodiments passes the packet to the virtualization layer 1327, which either identifies the flow-processing rule for a rule cache or passes the packet to a manager (executing on the smart NIC or on an external computer) that then determines the flow processing rule, and passes this rule back to the virtualization layer to use to forward the packet and to program the HOU. Once programmed, the VF can use the HOU to process subsequent packets of this flow.

FIG. 14 illustrates a process 1400 performed to process an egress NVMe command by the smart NIC 1320 of FIG. 13. In this example, the VM 1312 is presented an NVMe device through a virtual NVMe device emulation provided by the hypervisor 1314 (e.g., provided by a virtual NVMe device emulation module of the vSphere software of VMware Inc.). The NVMe device present in VM 1312 generates (at 1405) an NVMe command (with data). The VM's NVMe driver passes (at 1410) this NVMe command through the virtual device layer 1311 and the DSAN service layer 1313, to the kernel NVMe module 1315. At 1415, the kernel NVMe module 1315 identifies the NVMeOF controller that needs to process this NVMe command, and provides the packet to this controller 1316 or 1317.

The NVMEoRDMA 1316 or NVMEoTCP 1317 module running on the host (at 1420) converts the NVMe command to one or more NVMe network packets (NVMeOF packets) and passes the packets to a PF 1370 of the PCIe bus 150. At 1425, the PF 1370 adds PCIe header information to the NVMe network packets, and then passes the packets along the PCIe bus 150. The PCIe bus 150 creates a mapping between the PF 1370 and the VF module 1322 running on the smart NIC. Hence, the VF module 1322 receives each NVMeOF packet through the PCIe bus 150.

At 1430, the VFI module 1322 then transfers the NVMeOF packet either directly through the fast path to the NIC driver 1325, or indirectly to the NIC driver 1325 through the slow path that involves the virtual switch 1326. The NIC driver 1325 then forwards the NVMeOF packet through a shared port of the smart NIC, so that this packet can be forwarded through intervening network fabric (e.g., intervening switches/routers) to reach its destination external storage 1340. In some embodiments, the fast-path processing of the VF 1322 allows the VF to directly pass the packet to the shared port of the smart NIC. The process then ends.

FIG. 15 illustrates another way of using the smart NIC as a network accelerator in some embodiments. In this example, one VM 1512 executes the NVMeOF driver, so that it cannot only bypass the DSAN service layer 1313, but also the kernel NVMe 1315 and NVMeOF drivers 1316-17 of the host hypervisor 1514 that executes over a host OS 1500. This approach provides the fastest access for a VM to one or more external storages through the VM's NVMeOF driver, which in this example is a GOS NVMe fabric driver. However, in this approach, no local storage is emulated for the VM 1514 by either the host or the smart NIC. This VM simply accesses the external storages through its NVMeOF driver. Specifically, in the example of FIG. 15, the GOS NVMeOF driver inside the VM 1512 presents the NVMe device to the VM 1512. Also, a PF 1580 is directly assigned to VM 1512 using a passthrough mode, such as SRIOV Mode or SIOV Mode.

For the PF 1580, the smart NIC OS in FIG. 15 defines a VF 1523 to process the packets associated with the VM 1514. In both FIGS. 13 and 15, the smart NIC OS has a virtual switch 1326 to perform software switching operations and a network virtualization 1327 layer to perform network virtualization operations for the smart NIC. In some embodiments, these operations are analogous to the operations that traditionally have been performed on host computers to provide software switching and network virtualization operations. The smart NIC OS 1320 also has a NIC driver 1325 to communicate with the external storages 1340 through one or more ports of the smart NIC.

FIG. 16 illustrates a process 1600 that is performed to process egress packets from the VM 1512. As shown, the process starts (at 1605) when an application running on the VM 1512 generates an NVMe command (with data), and provides this command to the NVMeOF driver executing on this VM. This driver then coverts (at 1610) the NVMe command to a set of one or more network packets, which it then provides to the PF 1580 directly.

The PF 1580 provides (at 1615) the set of network packets that contains the NVMe command (with data) to the VF2 1523, which is a high speed network adapter provided by the smart NIC 1320. As described above for VF 1322 and operation 1430 of FIG. 14, the VF2 1523 (at 1620) transfers the set of network packets (containing the NVMe command/data) through the direct fast path or the indirect slow path, to a shared NIC port for forwarding to an external storage 1340. In some embodiments, the shared NIC port can be used by both VFs 1322 and 1523 as well as other modules of the smart NIC for other forwarding operations.

The smart NIC operating system in some embodiments is provided with the host-computer hypervisor program as part of a single downloaded package. For instance, some embodiments provide a method for provisioning a smart NIC with a smart NIC operating system for enabling resource sharing on the smart NIC connected to a host computer. The method, in some embodiments, is performed by the host computer and begins when the host computer receives (1) a host-computer hypervisor program for enabling resource sharing on the host computer and (2) the smart NIC operating system. In some embodiments, the host-computer hypervisor program includes the smart NIC hypervisor program. The host computer then installs the host-computer hypervisor program and provides the smart NIC operating system to the smart NIC for the smart NIC to install on the smart NIC. One of ordinary skill in the art will appreciate that a hypervisor program is used as an example of virtualization software (e.g., software enabling resource sharing for a device executing the software).

The smart NIC, in some embodiments, is a NIC that includes (i) an application-specific integrated circuit (ASIC), (ii) a general purpose central processing unit (CPU), and (iii) memory. The ASIC, in some embodiments, is an I/O ASIC that handles the processing of packets forwarded to and from the computer and is at least partly controlled by the CPU. The CPU executes a NIC operating system in some embodiments that controls the ASIC and can run other programs, such as API translation logic to enable the compute manager to communicate with a bare metal computer. The smart NIC also includes a configurable peripheral control interconnect express (PCIe) interface in order to connect to the other physical components of the bare metal computer system (e.g., the x86 CPU, memory, etc.). Via this configurable PCIe interface, the smart NIC can present itself to the bare metal computer system as a multitude of devices, including a packet processing NIC, a hard disk (using non-volatile memory express (NVMe) over PCIe), or other devices.

Although not necessary for managing a bare metal computer, the NIC operating system of some embodiments is capable of executing a virtualization program (similar to a hypervisor) that enables sharing resources (e.g., memory, CPU resources) of the smart NIC among multiple machines (e.g., VMs) if those VMs execute on the computer. The virtualization program can provide compute virtualization services and/or network virtualization services similar to a managed hypervisor. These network virtualization services, in some embodiments, include segregating data messages into different private (e.g., overlay) networks that are defined over the physical network (shared between the private networks), forwarding the data messages for these private networks (e.g., performing switching and/or routing operations), and/or performing middlebox services for the private networks.

The host-computer hypervisor program and the smart NIC operating system, in some embodiments, are programs that do not have previous versions installed on the computer or the smart NIC. In other embodiments, the host-computer hypervisor program and the smart NIC operating system received by the host computer are update programs for previously installed versions of the host-computer hypervisor program and the smart NIC operating system. After a host-computer hypervisor program and the smart NIC operating system are received, the host computer, in some embodiments, receives an additional program for updating the smart NIC operating system and provides the received program to the smart NIC for the smart NIC to update the smart NIC operating system.

In some embodiments, after receiving the host-computer hypervisor program and the smart NIC operating system, the host computer detects (or determines) that the host computer is connected to the smart NIC. In some embodiments, the connection is made over a standard PCIe connection and the smart NIC is detected as a peripheral device that supports the installation of the smart NIC operating system. The host computer provides, based on the detection, the smart NIC operating system to the smart NIC for the smart NIC to install. In some embodiments, the smart NIC operating system is sent to the smart NIC along with an instruction to the smart NIC to install the smart NIC operating system.

In some embodiments, the host computer includes a local controller that receives the host-computer hypervisor program and the smart NIC operating system. The local controller, in some embodiments, provides the host-computer hypervisor program and the smart NIC operating system to a compute agent that installs the host-computer hypervisor program on the host computer to enable the host computer to share resources among a set of compute nodes (e.g., virtual machines, containers, Pods, etc.). The host-computer hypervisor program and the smart NIC operating system are particular examples of virtualization software that is used, in some embodiments, to enabling resource sharing for the host computer and smart NIC, respectively.

As mentioned above, the smart NIC in some embodiments includes a set of ASICs, a general purpose CPU, and a memory. The set of ASICs, in some embodiments, includes an ASIC for processing packets forwarded to and from the host computer as well as other ASICs for accelerating operations performed by the smart NIC on behalf of the host computer (e.g., encryption, decryption, storage, security, etc.). The smart NIC operating system, in some embodiments, includes virtualization programs for network virtualization, compute virtualization, and storage virtualization. The virtualization programs, in some embodiments, enable sharing the resources of the smart NIC among multiple tenants of a multi-tenant datacenter.

The network virtualization program provides network virtualization services on the smart NIC. The network virtualization services, in some embodiments, include forwarding operations (e.g., network switching operations and network routing operations). The forwarding operations are performed, in some embodiments, on behalf of multiple logically separate networks implemented over a shared network of a datacenter. Forwarding packets for different logical networks, in some embodiments, includes segregating packets for each logically separate network into the different logically separate networks. Forwarding operations for the different logical networks, in some embodiments, are implemented as different processing pipelines that perform different sets of operations. The different sets of operations include, in some embodiments, different logical packet forwarding operations (e.g., logical switching, logical routing, logical bridging, etc.) and different middlebox services (e.g., a firewall service, a load balancing service, etc.).

The compute virtualization program, in some embodiments, provides virtualized compute resources (virtual machines, containers, Pods, etc.) that execute over the compute virtualization program. The storage virtualization program, in some embodiments, provides storage virtualization services on the smart NIC. The virtualized storage, in some embodiments, include one or multiple of virtual storage area networks (vSANs), virtual volumes (vVOLs), and other virtualized storage solutions. The virtualized storage appears to the connected host computer as a local storage, in some embodiments, even when the physical resources that are the backend of the virtualized storage are provided by a distributed set of storages of multiple physical host computers.

FIG. 17 conceptually illustrates an electronic system 1700 with which some embodiments of the invention are implemented. The electronic system 1700 can be used to execute any of the control, virtualization, or operating system applications described above. The electronic system 1700 may be a computer (e.g., a desktop computer, personal computer, tablet computer, server computer, mainframe, a blade computer etc.), phone, PDA, or any other sort of electronic device. Such an electronic system includes various types of computer readable media and interfaces for various other types of computer readable media. Electronic system 1700 includes a bus 1705, processing unit(s) 1710, a system memory 1725, a read-only memory 1730, a permanent storage device 1735, input devices 1740, and output devices 1745.

The bus 1705 collectively represents all system, peripheral, and chipset buses that communicatively connect the numerous internal devices of the electronic system 1700. For instance, the bus 1705 communicatively connects the processing unit(s) 1710 with the read-only memory 1730, the system memory 1725, and the permanent storage device 1735.

From these various memory units, the processing unit(s) 1710 retrieve instructions to execute and data to process in order to execute the processes of the invention. The processing unit(s) may be a single processor or a multi-core processor in different embodiments.

The read-only-memory (ROM) 1730 stores static data and instructions that are needed by the processing unit(s) 1710 and other modules of the electronic system. The permanent storage device 1735, on the other hand, is a read-and-write memory device. This device is a non-volatile memory unit that stores instructions and data even when the electronic system 1700 is off. Some embodiments of the invention use a mass-storage device (such as a magnetic or optical disk and its corresponding disk drive) as the permanent storage device 1735.

Other embodiments use a removable storage device (such as a floppy disk, flash drive, etc.) as the permanent storage device. Like the permanent storage device 1735, the system memory 1725 is a read-and-write memory device. However, unlike storage device 1735, the system memory is a volatile read-and-write memory, such a random access memory. The system memory 1725 stores some of the instructions and data that the processor needs at runtime. In some embodiments, the invention's processes are stored in the system memory 1725, the permanent storage device 1735, and/or the read-only memory 1730. From these various memory units, the processing unit(s) 1710 retrieve instructions to execute and data to process in order to execute the processes of some embodiments.

The bus 1705 also connects to the input and output devices 1740 and 1745. The input devices 1740 enable the user to communicate information and select commands to the electronic system. The input devices 1740 include alphanumeric keyboards and pointing devices (also called “cursor control devices”). The output devices 1745 display images generated by the electronic system 1700. The output devices 1745 include printers and display devices, such as cathode ray tubes (CRT) or liquid crystal displays (LCD). Some embodiments include devices such as a touchscreen that function as both input and output devices.

Finally, as shown in FIG. 17, bus 1705 also couples electronic system 1700 to a network 1765 through a network adapter (not shown). In this manner, the computer can be a part of a network of computers (such as a local area network (“LAN”), a wide area network (“WAN”), or an Intranet, or a network of networks, such as the Internet. Any or all components of electronic system 1700 may be used in conjunction with the invention.

Some embodiments include electronic components, such as microprocessors, storage and memory that store computer program instructions in a machine-readable or computer-readable medium (alternatively referred to as computer-readable storage media, machine-readable media, or machine-readable storage media). Some examples of such computer-readable media include RAM, ROM, read-only compact discs (CD-ROM), recordable compact discs (CD-R), rewritable compact discs (CD-RW), read-only digital versatile discs (e.g., DVD-ROM, dual-layer DVD-ROM), a variety of recordable/rewritable DVDs (e.g., DVD-RAM, DVD-RW, DVD+RW, etc.), flash memory (e.g., SD cards, mini-SD cards, micro-SD cards, etc.), magnetic and/or solid state hard drives, read-only and recordable Blu-Ray® discs, ultra-density optical discs, any other optical or magnetic media, and floppy disks. The computer-readable media may store a computer program that is executable by at least one processing unit and includes sets of instructions for performing various operations. Examples of computer programs or computer code include machine code, such as is produced by a compiler, and files including higher-level code that are executed by a computer, an electronic component, or a microprocessor using an interpreter.

While the above discussion primarily refers to microprocessor or multi-core processors that execute software, some embodiments are performed by one or more integrated circuits, such as application-specific integrated circuits (ASICs) or field-programmable gate arrays (FPGAs). In some embodiments, such integrated circuits execute instructions that are stored on the circuit itself.

As used in this specification, the terms “computer”, “server”, “processor”, and “memory” all refer to electronic or other technological devices. These terms exclude people or groups of people. For the purposes of the specification, the terms display or displaying means displaying on an electronic device. As used in this specification, the terms “computer readable medium,” “computer readable media,” and “machine readable medium” are entirely restricted to tangible, physical objects that store information in a form that is readable by a computer. These terms exclude any wireless signals, wired download signals, and any other ephemeral signals.

This specification refers throughout to computational and network environments that include virtual machines (VMs). However, virtual machines are merely one example of data compute nodes (DCNs) or data compute end nodes, also referred to as addressable nodes. DCNs may include non-virtualized physical hosts, virtual machines, containers that run on top of a host operating system without the need for a hypervisor or separate operating system, and hypervisor kernel network interface modules.

VMs, in some embodiments, operate with their own guest operating systems on a host using resources of the host virtualized by virtualization software (e.g., a hypervisor, virtual machine monitor, etc.). The tenant (i.e., the owner of the VM) can choose which applications to operate on top of the guest operating system. Some containers, on the other hand, are constructs that run on top of a host operating system without the need for a hypervisor or separate guest operating system. In some embodiments, the host operating system uses name spaces to isolate the containers from each other and therefore provides operating-system level segregation of the different groups of applications that operate within different containers. This segregation is akin to the VM segregation that is offered in hypervisor-virtualized environments that virtualize system hardware, and thus can be viewed as a form of virtualization that isolates different groups of applications that operate in different containers. Such containers are more lightweight than VMs.

Hypervisor kernel network interface modules, in some embodiments, are non-VM DCNs that include a network stack with a hypervisor kernel network interface and receive/transmit threads. One example of a hypervisor kernel network interface module is the vmknic module that is part of the ESXi™ hypervisor of VMware, Inc.

It should be understood that while the specification refers to VMs, the examples given could be any type of DCNs, including physical hosts, VMs, non-VM containers, and hypervisor kernel network interface modules. In fact, the example networks could include combinations of different types of DCNs in some embodiments.

While the invention has been described with reference to numerous specific details, one of ordinary skill in the art will recognize that the invention can be embodied in other specific forms without departing from the spirit of the invention. For instance, several examples were provided above by reference to specific distribute storage processes, such as vSAN. One of ordinary skill will realize that other embodiments use other distributed storage services (e.g., vVol offered by VMware, Inc.). The vSAN and vVol services of some embodiments are further described in U.S. Pat. Nos. 8,775,773 and 9,665,235, which are hereby incorporated by reference. Thus, one of ordinary skill in the art would understand that the invention is not to be limited by the foregoing illustrative details, but rather is to be defined by the appended claims. 

We claim:
 1. A method for providing a virtual machine executing on a host computer access to an external storage through a network interface card (NIC) connected to a bus of the host computer, the method comprising: defining a physical function (PF) module to represent a port of the NIC to the VM, said port for use in processing packets relating to storage access operations of the VM, said PF for execution by at least one processing unit of the host computer; configuring a network fabric storage driver on the VM to communicate with the PF in order to exchange packets relating to the storage access operations.
 2. The method of claim 1, wherein the storage access operations comprise read operations for reading data from the external storage and write operations for writing data to the external storage.
 3. The method of claim 1, wherein the network storage access driver is an NVMe (non-volatile memory access) over fabric (NVMeOF) driver.
 4. The method of claim 1, wherein the bus is a PCIe (peripheral component interconnect express) bus, and the PF module is a module defined through the PCIe bus.
 5. The method of claim 1 further comprising defining a virtual function (VF) module to associate with the PF and to execute with at least one processing unit of the NIC; passing storage access packets from the VM to the external storage through the PF, the bus, and the VF; passing storage access response packets from the external storage to the VM through the VF, the bus and the PF.
 6. The method of claim 5, wherein defining the VF comprises: configuring the VF to pass a first plurality of storage-access packets to a virtual switch along a slow packet-processing path when the VF does not have forwarding rules for processing the first plurality of packets; configuring the VF to pass a second plurality of storage-access packets to a port of the NIC along a fast packet-processing path when the VF has forwarding rules for processing the second plurality of packets.
 7. The method of claim 6, wherein the virtual switch provides forwarding rules to the VF after processing packets along the slow path.
 8. The method of claim 6, wherein the VF is a network accelerator that facilitates the forwarding of the packets related to the external storage.
 9. The method of claim 8, wherein configuring the VF comprises configuring the VF to use a hardware offload unit of the NIC to perform the fast path packet processing.
 10. The method of claim 1, wherein the VM is a first VM, the PF is a first PF, the network storage access driver is an NVMe (non-volatile memory access) over fabric (NVMeOF) driver, and the bus is a PCIe (peripheral component interconnect express) bus, the method further comprising defining a second PF module to represent the NIC port to a second VM, said port for use in processing packets relating to storage access operations of the second VM, said second PF for execution by at least one processing unit of the host computer; configuring an NVMe driver on a second VM to communicate with the second PF module in order to process storage access operations.
 11. A non-transitory machine readable medium storing a program for providing a virtual machine executing on a host computer access to an external storage through a network interface card (NIC) connected to a bus of the host computer, the program for execution by at least one processing unit of the NIC, the program comprising sets of instructions for: defining a physical function (PF) module to represent a port of the NIC to the VM, said port for use in processing packets relating to storage access operations of the VM, said PF for execution by at least one processing unit of the host computer; and configuring a network fabric storage driver on the VM to communicate with the PF in order to exchange packets relating to the storage access operations.
 12. The non-transitory machine readable medium of claim 11, wherein the storage access operations comprise read operations for reading data from the external storage and write operations for writing data to the external storage.
 13. The non-transitory machine readable medium of claim 11, wherein the network storage access driver is an NVMe (non-volatile memory access) over fabric (NVMeOF) driver.
 14. The non-transitory machine readable medium of claim 11, wherein the bus is a PCIe (peripheral component interconnect express) bus, and the PF module is a module defined through the PCIe bus.
 15. The non-transitory machine readable medium of claim 11, wherein the program further comprises sets of instructions for defining a virtual function (VF) module to associate with the PF and to execute with at least one processing unit of the NIC; passing storage access packets from the VM to the external storage through the PF, the bus, and the VF; and passing storage access response packets from the external storage to the VM through the VF, the bus and the PF.
 16. The non-transitory machine readable medium of claim 15, wherein the set of instructions for defining the VF comprises sets of instructions for: configuring the VF to pass a first plurality of storage-access packets to a virtual switch along a slow packet-processing path when the VF does not have forwarding rules for processing the first plurality of packets; and configuring the VF to pass a second plurality of storage-access packets to a port of the NIC along a fast packet-processing path when the VF has forwarding rules for processing the second plurality of packets.
 17. The non-transitory machine readable medium of claim 16, wherein the virtual switch provides forwarding rules to the VF after processing packets along the slow path.
 18. The non-transitory machine readable medium of claim 16, wherein the VF is a network accelerator that facilitates the forwarding of the packets related to the external storage.
 19. The non-transitory machine readable medium of claim 18, wherein the set of instructions for configuring the VF comprises a set of instructions for configuring the VF to use a hardware offload unit of the NIC to perform the fast path packet processing.
 20. The non-transitory machine readable medium of claim 11, wherein the VM is a first VM, the PF is a first PF, the network storage access driver is an NVMe (non-volatile memory access) over fabric (NVMeOF) driver, and the bus is a PCIe (peripheral component interconnect express) bus, the program further comprises sets of instructions for: defining a second PF module to represent the NIC port to a second VM, said port for use in processing packets relating to storage access operations of the second VM, said second PF for execution by at least one processing unit of the host computer; and configuring an NVMe driver on a second VM to communicate with the second PF module in order to process storage access operations. 